Sinkhole in the Codroy Valley.
Sinkhole in the Codroy valley, western Newfoundland. Sinkholes are funnel-shaped
depressions, or sinks, in the ground surface, commonly tens of metres in diameter.
They are found in areas where local rock can be slowly dissolved by water (e.g.
limestone, chalk, gypsum). They form when the roof of an underground cave
collapses or by surface solution.